Fusion welding apparatus for optical fiber

ABSTRACT

The present invention provides a compact fusion welding apparatus for optical fibers which has simple construction and which can stabilized discharges of discharge electrodes. Tip ends of a pair of the discharge electrodes (discharge forming ends) ( 5 ) are arranged so as to oppose each other via a space. Between tip ends of the discharge electrodes ( 1 ), connection end faces of a pair of optical fibers ( 2 ) are arranged so that the connection end faces thereof are opposed to each other and the connection end faces of the optical fibers ( 2 ) are fusion welded by discharge heat from the discharge electrodes ( 1 ). Dielectric bodies ( 4 ) are provided along the longitudinal direction of the discharge electrodes ( 1 ) in a form so as to sandwich the discharge electrodes ( 1 ) from both sides thereof. By means of the dielectric bodies ( 4 ), electric fields in the vicinity of the discharge forming ends ( 5 ) between the discharge electrodes ( 1 ) are stabilized and the swaying air between the discharge electrodes ( 1 ) is prevented, thereby the sway of discharge between the pair of discharge electrodes ( 1 ) is suppressed, and thus the discharges are stabilized.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part (CIP) of, and herebyincorporates in its entirety by reference, co-pending U.S. applicationSer. No. 09/651,817, entitled “FUSION WELDING APPARATUS FOR OPTICALFIBER”, filed Aug. 30, 2000, which claims priority to JapaneseApplication No. 11-244931, filed Aug. 31, 1999.

BACKGROUND OF THE INVENTION FIELD OF INVENTION

[0002] The present invention relates to a fusion welding apparatus foroptical fibers used for permanently connecting optical fibers to eachother.

[0003] As is common knowledge, fusion welding apparatuses for fusionwelding optical fibers by making use of high frequencies and highvoltage discharges are used and, in FIG. 6, an example of this type offusion welding apparatuses for optical fibers is shown. As shown in thesame figure, this type of fusion welding apparatus for optical fiberscomprises a pair of discharge electrodes (discharge electrode rods) 1for fusion welding optical fibers. In the apparatus illustrated in FIG.6, the discharge electrodes 1 are retained by a U-shaped electroderetaining member 14 and discharge forming ends 5 on the tip ends of thedischarge electrodes are arranged so as to oppose each other via aspace. Between the discharge electrodes 1, a pair of optical fibers 2are arranged so that connection end face sides thereof are opposed toeach other, and which are arranged, for example, so that the opticalaxis of the optical fibers and the axis of the discharge electrodes 1are roughly orthogonal to each other.

[0004] The optical fibers 2 are arrayed on the optical fiber arrayingmeans 13 in a condition where sheathes on the tip end sides are removedand bare optical fibers 6 are exposed. On the surface of the opticalfiber arraying means 13, V grooves 9 serving as optical fiber aligninggrooves to insert the bare optical fibers 6 are formed. Herein, in theapparatus illustrated in FIG. 6, the optical fiber arraying means 13 areformed in the U-shape and the electrode retaining means 14 is fixed on aU-shaped concave portion 25 of the optical fiber arraying means 13.

[0005] Also, on the pair of discharge electrodes 1, a power source fordischarge (not illustrated) is connected and by driving the power sourcefor discharge, the connection end faces of the optical fibers 2 arefusion welded by discharge heat from the discharge electrodes 1.

[0006] Incidentally, in the abovementioned fusion welding apparatus foroptical fibers, as shown in FIG. 7A, it is desirable that discharges Abetween the pair of electrodes 1 are stable, however, in actual fact, asshown in FIG. 7B and FIG. 7C, a phenomena where the discharges A swayand become unstable is recognized.

[0007] As a factor of the sway of the discharges A, the sway of the airdue to the wind can be considered. In addition, as another factor of thesway of the discharges A, it is considered that electric fieldconditions surrounding the discharges change due to changes in theenvironment inside the fusion welding apparatus etc., thereby thelocation of the discharges is distorted or shifted. That is, in thefusion welding apparatus for optical fibers, for example, fusionmechanism portions such as an alignment mechanism (not illustrated) ofthe optical fibers 2 are provided, and it is considered that positionsof these mechanism portions slightly change in each connecting operationand electric field conditions surrounding the discharges change due tosubtle balance of an incorporated position of each portion of the fusionmechanism portion, thereby the location of the discharges is distortedand shifted.

[0008] Therefore, in order to prevent the discharges A from swayingunder the influence of the wind, as shown in FIG. 8, a fusion weldingapparatus for optical fibers which is provided with a windshield cover12 for covering the connection end face sides of the optical fibers 2,discharge electrodes 1, optical fiber arraying means 13, and electroderetaining member 14 as a whole has been suggested.

[0009] Also, as shown in FIG. 9 and FIG. 10, fusion welding apparatusesfor optical fibers which are provided with magnetic field controlmechanisms for suppressing {compensating) the sway of the discharges Aby controlling magnetic fields have been suggested. In the fusionwelding apparatus for optical fibers as shown in FIG. 9, a coil 10 iswound around a magnetic core 23 for horizontal deflection and when apower source for discharge 8 is driven, a high frequency current issupplied with the coil 10, whereby magnetic fields are generated in agap 24 of the magnetic core 23, thereby the sway of the dischargesbetween the discharge electrodes 1 has been suppressed.

[0010] In the fusion welding apparatus for optical fibers as shown inFIG. 10, the magnetic core 23 and coil 10 for horizontal deflection arereplaced with a magnetic core 23 and a coil 10 for vertical deflection,and by an effect similar to the case of FIG. 9, the sway of thedischarges A is suppressed. Furthermore, in FIG. 9 and FIG. 10, 3denotes a fiber cramp for cramping the optical fibers 2 and 16 denotes adriving unit.

[0011] However, as shown in FIG. 8, in the apparatus provided with thewindshield cover 12, the sway of the discharges between the dischargeelectrodes 1 due to the wind can be suppressed, whereas the sway of thedischarges between the discharge electrodes due to other factors cannotbe suppressed, therefore, there have been many cases where the sway ofthe discharges between the discharge electrodes 1 cannot completely besuppressed. In addition, since such fusion welding apparatuses foroptical fibers as described above are used for lay work of opticalfibers, etc. to make the apparatuses lightweight and compact isdemanded, however, in terms of the apparatuses shown in FIG. 9 and FIG.10, there have been problems such that the apparatuses increase in sizesince the mechanisms for magnetic field control are provided and,moreover, the apparatuses have no practical use due to the large powerconsumption thereof.

SUMMARY OF THE INVENTION

[0012] The present invention is made for solving the above-describedconventional problems as described above, and the object thereof is toprovide a compact fusion welding apparatus for optical fibers which hasa simple construction and which can stabilize discharges betweendischarge electrodes.

[0013] In order to achieve the above-described object, the presentinvention provides a fusion welding apparatus for optical fibers havingthe following construction. That is, a fusion welding apparatus foroptical fibers according to the present invention is constructed so thata pair of discharge electrode tip ends, to which optical fibers arefusion welded, are arranged to oppose each other via a space, andconnection end faces of a pair of optical fibers, which are arranged sothat the connection end face sides thereof are opposed to each otherbetween the discharge electrode tip end faces, are fusion welded bydischarge heat from the discharge electrodes, wherein; dielectric bodiesfor suppressing the sway of discharges between the pair of dischargeelectrodes are provided.

[0014] Preferably, the dielectric bodies are provided along thelongitudinal direction of the pair of discharge electrodes in a form soas to sandwich said pair of discharge electrodes from both sidesthereof.

[0015] Furthermore, if necessary, in addition to providing thedielectric bodies, a windshield cover for covering, at least, a spacebetween the discharge electrode tip ends and optical fiber connectionend face sides is provided.

[0016] As an example mode of the present embodiment, the dielectricbodies are attached inside the windshield cover. And as a preferableexample mode, the windshield cover is an open-and-close type cover whichopens and closes by rotations around a spindle as its fulcrum and by aclosing operation of the windshield cover, the pair of dielectric bodiesare arranged along the longitudinal direction of the dischargeelectrodes at positions so as to sandwich said discharge electrodes fromboth sides thereof.

[0017] In the fusion welding apparatuses for optical fibers according tothe present invention and prior art, electric fields as shown in FIG. 3Agenerate when a current flows between the pair of discharge electrodesarranged so that the tip ends oppose each other via the space. Namely anX axis shown in FIG. 3A corresponds to the axial center of the pair ofdischarge electrodes. When an axis which goes through the center betweenthe discharge electrode tip ends and which is orthogonal to the X axisis provided as a Y axis so that space coordinates in terms of X and Yare formed, electric lines of force are shown by dashed lines while theequipotential lines are shown by solid lines in this space coordinates.Herein, q denotes a positive charge, −q denotes an negative charge, aposition of the discharge forming end (tip end) of one of the pair ofdischarge electrodes is the position shown by q in the figure, and aposition of the discharge forming end (tip end) of the other dischargeelectrode is the position shown by −q in the figure.

[0018] However, such electrical fields are changeable due to the abovedescribed changes in the environment inside the fusion welding apparatusand the electrical fields are unstable, therefore, it is considered thatthe discharges between the discharge electrodes sway when electric fieldconditions surrounding the discharge electrodes change.

[0019] Also, it is considered that the sway of the discharges alsooccurs, as described above, due to the sway of the air between thedischarge electrodes.

[0020] With respect to problems, according to the present invention, thedielectric bodies (solid dielectrics) which suppress destabilization ofthe electric fields and the sway of the air at the same time andsuppress the sway of the discharges between the pair of dischargeelectrodes, thereby enabling suppression of the sway of the dischargesbetween the discharge electrodes, thus enabling stabilization of thedischarges.

[0021] Hereinafter, the suppressive effects for the sway of thedischarges between the discharge electrodes by means of the dielectricbodies will be described. Since dielectrics polarize when they arepresent in electric fields, for example, as shown in FIG. 3B, thedielectrics polarize when electric lines of force pass therethrough.Accordingly, in the electric fields as shown in FIG. 3A, when dielectricbodies 4 are provided along the longitudinal direction of dischargeelectrodes 1 in a form so as to sandwich discharge forming ends 5 of thedischarge electrodes 1 from both sides thereof as shown in FIG. 2, thedielectric bodies 4 polarize as shown in FIG. 2 due to the electriclines of force shown by the dashed lines.

[0022] Thus, in the present invention, it is considered that thedielectric bodies polarize as described above, thereby enabling theprovision of effects similar to those in a case where the vicinities ofthe dielectric electrodes are shielded, and thereby the electric fieldconditions in the vicinities of the discharges are allowed to lock, andtherefore it is considered that the sway of the discharges caused by thesway of the electric fields can be suppressed.

[0023] Furthermore, by setting a distance L between the dielectricbodies (refer to FIG. 1) to the same degree as the distance between thedischarge electrode tip ends or to a lower degree, the electric fieldsinside the dielectric bodies also take regulation effects and byadjusting the central position of the distance between the twodielectric bodies so as to coincide with the axial center of thedielectric electrodes, the discharges between the discharge electrodesare stably formed around the axial center of the discharge electrodes asshown in FIG. 7A.

[0024] Moreover, by providing the dielectric electrodes, the air aroundthe dielectric electrodes decreases, whereby a flow of air between thedischarge electrodes is suppressed accordingly and then, the sway of thedischarges due to the sway of the air is suppressed. In particular, bysetting the distance L between the dielectric bodies to 3 mm or less,occurrence of convection of the air which exists in the space betweenthe dielectric bodies is significantly suppressed.

[0025] According to the above descriptions, in the present invention,the sway of the discharges between the pair of discharge electrodes issuppressed and the discharges between the discharge electrodes arestabilized. In particular, according to the present invention, forexample, by providing the dielectric bodies along the longitudinaldirection of the pair of discharge electrodes whose tip ends arearranged so as to oppose each other via the space in a form so as tosandwich the discharge electrodes from both sides thereof, electricfields which generate when a current flows can be stabilized by actionsof the dielectric bodies.

[0026] Furthermore, since the dielectric bodies are provided, the air inthe vicinity of the discharge forming portions of the dischargeelectrodes decreases, thereby the sway of the air between the dischargeelectrodes is suppressed. As a result, the sway of the dischargesbetween the discharge electrodes is suppressed, thus the discharges arestabilized.

[0027] Also, in the present invention, by a simple composition, forexample, such that the dielectric bodies are provided along thelongitudinal direction of the pair of discharge electrodes in a form soas to sandwich said discharge electrodes from both sides thereof,stabilization of the discharges between the pair of discharge electrodescan be realized, therefore, no large-scale control mechanism such as amagnetic field control mechanism is necessary, and thus the apparatuscan be made compact.

[0028] Furthermore, in terms of the apparatus wherein the windshieldcover is provided, since the sway of the air between the dielectricelectrodes due to the wind, etc. can be suppressed, the sway of thedischarges between the dielectric electrodes can be suppressed moresecurely, thereby the discharge can be stabilized.

[0029] Furthermore, in terms of the apparatus wherein the dielectricbodies are attached inside the windshield cover, since the dielectricbodies can be arranged at appropriate positions in accordance with theopening and closing operations of the windshield cover, the arrangementoperations of the dielectric bodies can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Exemplary embodiments of the invention will now be described inconjunction with the drawings in which;

[0031]FIG. 1 is a major portion constructional view shown in aperspective view showing a first embodiment of the fusion weldingapparatus for optical fibers according to the present invention.

[0032]FIG. 2 is an explanatory view in a plan schematically showing anarrangement of the dielectric bodies 4 and the electrical fields in thevicinity of the discharge forming ends 5 of discharge electrodes 1 inthe above-mentioned embodiment.

[0033]FIG. 3A is an explanatory view showing electrical fields in thevicinity of discharge forming ends of a pair of discharge electrodes andFIG. 3B is an explanatory view showing a condition where the electricfields pass through a dielectric and the following polarized conditionof the dielectric, respectively.

[0034]FIG. 4 is a major portion constructional view shown in aperspective view showing a second embodiment of the fusion weldingapparatus for optical fibers according to the present invention.

[0035]FIG. 5 is an explanatory view showing a form of the dielectricbodies in another embodiment of the fusion welding apparatus for opticalfibers according to the present invention along with the dischargeelectrodes.

[0036]FIG. 6 is an explanatory view showing a construction of the fusionwelding apparatus for optical fibers according to the prior art.

[0037]FIG. 7A, FIG. 7B, and FIG. 7C are explanatory views showingvarious exemplary conditions of discharges between pairs of dischargeelectrodes.

[0038]FIG. 8 is an explanatory view showing the prior art fusion weldingapparatus for optical fibers which is provided with the windshieldcover.

[0039]FIG. 9 is an explanatory view showing an example of the prior-artfusion welding apparatus for optical fibers which is provided with amagnetic field control unit.

[0040]FIG. 10 is an explanatory view showing another example of theprior art fusion welding apparatus for optical fibers which is providedwith a magnetic field control unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0041] Hereinafter, the present invention will be described in detailbased on preferred embodiments with reference to the attached drawings.Here, in the descriptions of the present embodiments, the same symbolsare used for portions of the same name as those of the prior art andrepeated description thereof will be omitted or simplified. In FIG. 1, amajor portion construction of a first embodiment of the fusion weldingapparatus for optical fibers according to the present invention isillustrated.

[0042] As shown in FIG. 1, in the present invention, the dischargeelectrodes 1 and optical fiber arraying means 13, etc. are constructedin almost the same manner as those in the prior art fusion weldingapparatus for optical fibers shown in FIG. 6. Unlike the prior art, whatis featured in the present invention is that the dielectric bodies 4 forsuppressing the sway of the discharges between the pair of dischargeelectrodes 1 are provided along the longitudinal direction of thedischarge electrodes 1 in a form so as to sandwich the dischargeelectrodes 1 from both sides thereof.

[0043] In one embodiment, the dielectric bodies 4 are formed ofzirconium ceramic plates, for example. It is desirable to select adielectric body that is characterized by a dielectric constant of atleast 10 (at 1 MHz). For example in one embodiment, the dielectricbodies 4 may comprise a material having a dielectric constant of 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, or any rangeselected within such dielectric constants. It is noted that the higherthe dielectric constant of the dielectric bodies 4, the more likely theelectric field will lock sufficiently in the vicinity of the dischargesA (see FIG. 2). The distance L between the pair of dielectric bodies 4is set to 3 mm and the dielectric bodies 4 are arranged so that thecentral position of the space and the axial center of the dischargeelectrodes 1 coincide with each other. Also, on the lower portion sideof the dielectric bodies 4, aperture portions 20 through which barefibers 9 of the optical fibers 2 are inserted are formed, respectively.Herein, in the present embodiment, the tip end distance M of thedischarge electrodes 1 is set to 2.6 mm.

[0044] The present embodiment is constructed as described above andconnection end face sides of the optical fibers are fusion welded byoperations similar to those in the prior art in the present embodimentas well. However, since the dielectric bodies 4 are provided along thelongitudinal direction of the discharge electrodes 1 in a form so as tosandwich the discharge forming ends 5 of the discharge electrodes 1 fromboth sides thereof, the dielectric bodies 4 polarize as shown in FIG. 2,thereby the electric fields between the discharge electrodes 1 arestabilized. Consequently, the sway of the discharges due to the sway ofthe electric fields is suppressed.

[0045] In particular, according to the present embodiment, the distanceL between the dielectric electrodes is set to 3.0 mm so as to be anapproximate value to the distance between the discharge electrode tipends of 2.6 mm, thereby the electric fields inside the dielectric bodies4 also take the regulation effects. And, in the present invention, sincethe central position of the distance L between the two dielectric bodies4 is made coincide with the axial center of the discharge electrodes 1,the center of the discharges between the discharge electrodes 1 can bemade coincide with the axial center of the discharge electrodes, thusthe sway of the discharges due to the sway of the electric fields can bemore securely suppressed.

[0046] Also, in the present invention, since the dielectric bodies 4 areprovided, the air around the discharge electrodes 1 such as the vicinityof the discharge forming portions 5 of the discharge electrodes 1 can bereduced, whereby the flow of air between the discharge electrodes can besuppressed accordingly, therefore the sway of the discharges due to thesway of the air can be suppressed.

[0047] In particular, the present inventor has confirmed that by settingthe distance L between the dielectric bodies 4 to 3 mm or less,occurrence of convection of the air which exists in the space betweenthe dielectric bodies is significantly suppressed. Based on the fact,the distance L between the dielectric bodies 4 is set to 3 mm or less inthe present embodiment, therefore the sway of the discharges due to thesway of the air can be securely suppressed.

[0048] As has been described above, according to the present embodiment,both the sway of the discharges due to the sway of the electric fieldsand sway of the discharges due to the sway of the air can be suppressedand the discharges between the discharge electrodes 1 can be stabilized.In fact, when the present inventor performed fusion welding for opticalfibers by means of the fusion welding apparatus for optical fibers ofthe present embodiment, the discharges between the discharge electrodes1 could be stabilized at all times, thereby it was confirmed that fusionwelding of the optical fibers can be highly reliably performed.

[0049] Furthermore, in the present invention, by a simple compositionsuch that the dielectric bodies 4 are provided so as to sandwich thedischarge electrodes 1 from both sides thereof, stabilization of thedischarges can be realized, and therefore, no large-scale controlmechanism such as the magnetic field control mechanism is necessary,thus the apparatus can be made compact.

[0050] In FIG. 4, a major portion construction of a second embodiment ofthe fusion welding apparatus for optical fibers according to theinvention is illustrated. Here, in the descriptions of the secondembodiment, the same symbols are used for portions of the same name asthose of the prior art and the first embodiment and repeated descriptionthereof will be omitted or simplified.

[0051] In the second embodiment, a fusion welding apparatus for opticalfibers is constructed in almost the same manner as that in theabove-mentioned first embodiment. Unlike the first embodiment, thefeature of the second embodiment is that the windshield cover 12 forcovering the connection end face sides of the optical fibers 2, pair ofdischarge electrodes 1, optical fiber arraying means 13, and electroderetaining member 14 as a whole is provided, and the dielectric bodies 4are provided inside the windshield cover 12 in the second embodiment.Herein, the windshield cover 12 is provided so that it can freely rotatearound the spindle 19 as its fulcrum in the direction of arrow B to openand close, and which is constructed so as to be automatically opened andclosed.

[0052] The second embodiment is constructed as described above and inaccordance with the opening and closing movements of the windshieldcover 12, the dielectric bodies 4 move as one body. That is, when theoptical fibers 2 are fusion welded by means of the fusion weldingapparatus for optical fibers of the second embodiment, the dischargeelectrodes 1 and optical fibers 2 are set in a condition where thewindshield cover 12 is opened, thereafter the windshield cover 12 isrotated around the spindle 19 as its fulcrum and brought into a closedcondition. As a result, at this time, the dielectric bodies 4 arearranged along the longitudinal direction of the discharge electrodes 1at appropriate positions in a form so as to sandwich the dischargeelectrodes 1 from both sides thereof.

[0053] Similar to the first embodiment, by providing the dielectricbodies 4, effects similar to those of the first embodiment can beprovided in the second embodiment as well. Also, in the secondembodiment, the sway of the air can be suppressed more securely byproviding the windshield cover 12, thereby the sway of the discharges ofthe discharge electrodes 1 can be more effectively suppressed.

[0054] In addition, in the second embodiment, the dielectric bodies 4are attached inside the windshield cover 12 so that they move along withthe windshield cover 12 as one body, therefore the arrangementoperations of the dielectric bodies 4 can be simplified.

[0055] The present invention is not limited to the above-describedembodiments but various other embodiments can be taken. For example, inthe second embodiment, the windshield cover 12 is provided so as to befreely rotatable around the spindle 19 as its fulcrum, however, forexample, the windshield cover 12 may be arranged by manually moving itfrom the upper portion side of the optical fibers 2, etc. to the lowerside thereof.

[0056] Also, in the second embodiment, the whole discharge electrodes 1are covered by the windshield cover 12, however it is sufficient thatthe windshield cover 12 is constructed so as to cover, at least, thespace between the tip ends of the discharge electrodes 1 and theconnection end face sides of the optical fibers 2. Nevertheless, whenthe whole discharge electrodes 1 and optical fiber arraying means 13,etc. are covered by the windshield cover 12 as in the second embodiment,the flow of air between the discharge electrodes 1 is easily suppressed,and by making use of the conventional generally used windshield cover 12and attaching the dielectric bodies 4 on the windshield cover 12, theconstruction of the present invention can be easily achieved.

[0057] Furthermore, in each of the first and second embodiments, thedistance L between the dielectric bodies 4 is set to 3 mm, however, thedistance L between the dielectric bodies 4 is not particularly limitedand can be appropriately set. Nonetheless, by setting the distance L ofthe dielectric bodies 4 to 3 mm or less, convection of the air whichexists in the space between the discharge bodies 4 can be easilysuppressed, furthermore, by setting the distance L between thedielectric bodies 4 to the same degree as the distance between the tipends of the discharge electrodes 1 or a lower degree, as describedbefore, the sway of the electric fields in the vicinity of the dischargeelectrodes 1 is suppressed, whereby the discharges between thedielectric electrodes 1 can be easily suppressed.

[0058] Furthermore, in each of the embodiments, the plate-shapeddielectric bodies 4 are provided along the longitudinal direction of thedischarge electrodes 1 in a form so as to sandwich the dischargeelectrodes 1 from both sides thereof, however, for example, as shown inFIG. 5, the U-shaped dielectric bodies which sandwich the dischargeelectrodes 1 from both sides thereof may be provided along thelongitudinal direction of the discharge electrodes 1 so that the upperand lower sides of the discharge electrodes 1 are also surrounded by thedielectric bodies 4. By such a method, the discharges can be stabilizedalso in the vertical direction of the discharge electrodes 1, therebythe discharge between the discharge electrodes 1 can become still morestabile.

[0059] Furthermore, in each of the embodiments, an example where one ofthe optical fibers 2 is opposed to the other and these optical fibers 2are fusion welded to each other is described, however, the fusionwelding apparatus for optical fibers according to the present inventioncan also be applied to an apparatus which makes a plurality of pairs ofoptical fibers 2 oppose each other and fusion welds these optical fibers2 collectively.

[0060] Furthermore, in the present embodiment, the optical fiberarraying means has a U-shape, however, the present invention can also beapplied in an optical fiber alignment type apparatus wherein therespective V groove portions are separated so that positioning can beperformed independently.

What is claimed is:
 1. A fusion welding apparatus for optical fibers,the apparatus comprising: a pair of discharge electrode tip endsarranged opposite to each other and separated by a space, whereinconnection end faces of a pair of optical fibers are arranged to befusion welded by discharge heat from the discharge electrodes, andwherein a plurality of dielectric bodies are provided to suppress thesway of discharges between the pair of discharge electrodes, and furtherwherein the dielectric bodies are polarized by receiving electric linesof force of the discharges from the discharge electrodes to lock theelectric field conditions of the discharge area, and wherein thedielectric constant of said dielectric bodies is at least ten (10). 2.The fusion welding apparatus as set forth in claim 1, wherein thedielectric bodies are provided along the longitudinal direction of thepair of discharge electrodes so as to sandwich said discharge electrodesfrom both ends thereof.
 3. The fusion welding apparatus as set forth inclaim 1, wherein a windshield cover is provided to cover the spacebetween the discharge electrode tip ends and optical fiber connectionend face sides.
 4. The fusion welding apparatus as set forth in claim 2,wherein a windshield cover is provided to cover the space between thedischarge electrode tip ends and optical fiber connection end facesides.
 5. The fusion welding apparatus as set forth in claim 3, whereinthe dielectric bodies are attached to the windshield cover.
 6. Thefusion welding apparatus as set forth in claim 3, wherein the dielectricbodies are attached to the windshield cover.